Enable version checks on session database
The session database, like the jmdictdb databases, has a version table that the api can check to confirm it is able to understand the schema version. However such checking is currently disabled by the inclusion of argument "noverchk=True" in all the jdb.dbOpenSvc() calls for the session database since there in no ability to define a second database version number in addition to the jmdictdb version number in lib/dbver.py. At the current time there are jdb.dbOpenSvc calls for the session database in jmcgi.parseform(), jmcgi.get_user(), cgi/users.py, cgi/userupd.py.
Need to allow for the definition of a second version number (in dbver.py) for the session database and check it when opening the session database.